title: Liver abscesses in feedlot cattle: a review.
abstract: Liver abscesses in slaughtered beef cattle result from aggressive grain-feeding programs. The incidence, averaging from 12 to 32% in most feedlots, is influenced by a number of dietary and management factors. Liver abscesses represent a major economic liability to producers, packers, and ultimately consumers. Besides liver condemnation, economic impacts include reduced feed intake, reduced weight gain, decreased feed efficiency, and decreased carcass yield. Fusobacterium necrophorum, a member of the ruminal anaerobic bacterial flora, is the primary etiologic agent. Actinomyces pyogenes is the second most frequently isolated pathogen. Ruminal lesions resulting from acidosis generally are accepted as the predisposing factors for liver abscesses. F. necrophorum possesses or produces a number of virulence factors that participate in the penetration and colonization of the ruminal epithelium and subsequent entry and establishment of infection in the liver. However, only a few virulence factors have been characterized well. Control of liver abscesses in feedlot cattle generally has depended on the use of antimicrobial compounds. Five antibiotics (i.e., bacitracin methylene disalicylate, chlortetracycline, oxytetracycline, tylosin, and virginiamycin) are approved for prevention of liver abscesses in feedlot cattle. Tylosin is the most effective and the most commonly used feed additive. Tylosin feeding reduces abscess incidence by 40 to 70%. The mode of action of antibiotics in preventing liver abscesses is believed to be via inhibition of ruminal F. necrophorum. Protective immunity against F. necrophorum induced by a variety of antigenic components has ranged from ineffectual to significant protection.
authors.affiliation: Department of Animal Sciences, Kansas State University, Manhattan 66506, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Nagaraja
authors.forename: M M
authors.initials: MM
authors.lastname: Chengappa
mesh_terms: D000190:Actinomyces / Q000302:isolation & purification; D000196:Actinomycosis / Q000188:drug therapy / Q000662:veterinary; D000822:Animal Husbandry / Q000191:economics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000209:etiology* / Q000517:prevention & control; D005503:Food Additives; D005674:Fusobacterium Infections / Q000188:drug therapy / Q000662:veterinary; D005675:Fusobacterium necrophorum / Q000302:isolation & purification; D006128:Growth / Q000502:physiology; D015994:Incidence; D008099:Liver / Q000382:microbiology / Q000473:pathology / Q000503:physiopathology; D008100:Liver Abscess / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D008460:Meat / Q000592:standards; D012417:Rumen / Q000382:microbiology / Q000473:pathology / Q000503:physiopathology; D012720:Severity of Illness Index; D015645:Tylosin / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D005503:Food Additives; D015645:Tylosin